A composite optical element in which a transparent thermoplastic resin material is integrated with one surface of a transparent glass material has been produced practically. Examples of the composite optical element include an optical element produced by molding a resin material as a spacer between two glass lenses and an optical element produced by molding, on one surface of a glass plate, a resin material imparted with special optical properties into an optical waveguide or a prism.
PTL 1 discloses a technology for molding a composite optical element by performing injection molding of a thermoplastic resin material in a mold in which a glass substrate is placed. Moreover, PTL 2 discloses a technology for producing a composite optical element by forming a resin layer by performing injection molding of a resin material on a glass substrate and then cutting the contour of the resin layer so as for the contour to have a desired aspherical surface, followed by polishing.
PTL 3 discloses a technology for molding a composite optical element under compression by pressing a glass substrate supported by an upper mold onto a molten resin material placed in a lower mold from above, followed by heating under pressure.